Plastic substrates are commonly used in automotive parts and accessories, containers, household appliances, and other commercial items. Organic coating compositions are very often applied to these substrates for decorative and protective purposes. These plastic substrates are made of a variety of thermosetting and thermoplastic materials having widely varying surface properties including surface tension, roughness, and flexibility, which make it difficult to achieve adequate adhesion of organic coatings to such materials, particularly after aging or environmental exposure of the plastic materials. It is desirable to have a coating composition which can be used to coat various plastic substrates in order to promote adhesion of subsequently applied coatings on the substrate.
Moreover, in automotive applications, it is desirable to provide a coating composition which exhibits compatibility with subsequently applied coatings, stability with respect to long-term storage, resistance to gasoline, acids, and other chemicals, resistance to humidity, and excellent appearance.